<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

</head>
<body>











<script>
    /*弹出警告框*/
    alert("hello js")//写入警告框


    /*输出语句*/
    document.write("hello js 2~");//写入html界面

    console.log("hello js3~");//写入浏览器控制台
</script>
<!--
<script src="../js/demo.js"></script>
-->
</body>
</html>

